Safety management systems in aviation maintenance (descriptive statistics) - 1997

PEREZGONZALEZ Jose D (1997). Safety management systems in aviation maintenance (descriptive statistics). Knowledge (ISSN 2324-1624), 2013, pages 18-21. [DOI] [Printer friendly]

AMO's SMS

McDonald et al analyzed the safety management systems of four aircraft maintenance organizations (AMOs)3 in 19972. This article presents newly re-worked descriptive results about that research.

Illustration 1 tabulates the main results so that each AMO (columns) gets ranked within each safety variable (rows). Rankings are in ascending order, with poor performance attracting lower rankings (eg, 1 or -4) and good performance attracting higher rankings (eg, 4 or -1). This procedure allows for adding up each organization's ranking at the bottom of the table to gain an appreciation of how good the organization is overall. The procedure also allows for setting an ordinal effect size of approximately 15 units on the resulting scale as a big effect size5.

Illustration 1 shows that there were sensible differences in safety management styles among the four organizations. Organization C, the best organization in the group, achieved position 43 on the scale (out of 50). At a sensible distance (15 units on the scale) was organization A in position 28, followed by organization B, also at a relatively sensible distance (12 units on the scale), in position 16. Organization D, the worst organization in the group, achieved position 10, only slightly lower (6 units on the scale) than organization D .

Illustration 1: Elements of safety management across four aircraft maintenance organizations
SMS elements A B C D
Safety policy 3, Good 2, Basic 4, Strong 1, Ineffective
Safety standards 2, Good 1, Basic 3, Strong 1, Basic
Planning & documentation 3, Good 2, Improving 4, Strong 1, Ineffective
Management training 2, Partly effective 1, Inconsistent 3, Effective 1, Ineffective
Auditing 1, Statutory 2, Basic 3, Strong 1, Statutory
Reporting 3, Backlogged 1, Starting 1, Starting 2, Poor
Incident investigation 3, Good 2, Ineffective 4, Strong 1, Absent
Feedback 3, Good 2, Ineffective 4, Strong 1, Poor
Change 3, Good 2, Ineffective 4, Strong 1, Absent
( SMS quality ) ( 23 ) ( 15 ) ( 30 ) ( 10 )
Climate & attitudes A B C D
Safety climate 3, Slightly positive 1, Negative 4, Positive 2, Slightly negative
Safety attitudes 2, Better 2, Better 2, Better 1, Good
( safety climate ) ( 5 ) ( 3 ) ( 6 ) ( 3 )
Disciplinary actions4 A B C D
Impartial investigation 3, ≃53% 2, ≃35% 4, ≃62% 1, ≃28%
Incident discussed 3, ≃40% 1, ≃23% 4, ≃51% 2, =33%
Verbal reprimand -2, ≃10% -2, ≃10% -3, ≃15% -1, ≃7%
None -3, ≃3% -4, ≃4% -1, ≃0% -2, ≃3%
Disciplinary hearing -4, ≃45% -1, ≃23% -2, ≃35% -3, =37%
Suspension of license -2, =15% -4, =51% -1, ≃8% -3, ≃18%
Suspension of job -4, =19% -2, ≃9% -1, ≃3% -3, ≃13%
Disciplinary culture
( positive discipline ) ( 6 ) ( 3 ) ( 8 ) ( 3 )
( negative discipline ) ( -15 ) ( -13 ) ( -8 ) ( -12 )
Task procedures A B C D
Reported violations -1, =30% -2, =36% -3, =37% -4, =47%
( behavior ) ( -1 ) ( -2 ) ( -3 ) ( -4 )
SMS & culture (0-50) 28 16 43 10
Ordinal small medium large ( Prototype diff. )
effect size5 5 10 15 ( 16 )

Illustration 2 summarizes the correlations found between above groups of safety elements. In order to facilitate interpretation of the results, all ranks were transformed into positive values.

Illustration 2: Correlations (Spearman)
rho SMS Climate +Discipline -Discipline
Climate .949
+Discipline .949 1.000
-Discipline -.200 -.316 -.316
-Behavior -.400 -.211 -.211 -.800

As illustration 2 shows, there were high and positive ranked correlations6 between SMS, organizational climate, and positive discipline, which suggest that better safety management systems went together with better climate and more constructive disciplinary cultures (and viceversa) among these four organizations. Smaller and negative correlations appeared between above groups of variables and negative disciplinary expectations and violations, which also hint to relationships between better SMS, climates and constructive cultures and lower rates of negative disciplinary expectations and lower reported violations. Notwithstanding this, there was also a relatively high and negative correlation between preference for punitive disciplinary actions and the amount of reported violations.

Although little can be generalized from this particular research, above results describe a situation were safety management and safety culture did not appear standardized among similar organizations doing similar jobs and having similar responsibilities for aviation safety. Safety management and safety culture appeared as quite variable, with little cross-over across organizations, at least at the time of the research.

On the other hand, safety management and safety culture also appeared as quite consistent within each organization, further suggesting that the quality of the management system and the safety culture was idiosyncratic to each organization, was coherent within it, and permeated all levels in that organization.


Author

Jose D PEREZGONZALEZ (2012). Massey University, Turitea Campus, Private Bag 11-222, Palmerston North 4442, New Zealand. (JDPerezgonzalezJDPerezgonzalez).

Want to know more?

FAA - Safety Management System
This FAA website provides more information about safety management systems in aviation.
Wiki of Science - Safety management systems in aviation maintenance (introduction)
This Wiki of Science page is an accompanying introduction to above article.

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